% This is the cweb file extconv.w of the CJK Package Ver. 4.8.5  16-Oct-2021

% Copyright (C) 1994-2021  Werner Lemberg <wl@@gnu.org>
%
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program in doc/COPYING; if not, write to the Free
% Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
% MA 02110-1301 USA

% To print this CWEB file you should (but not must) use the CWEAVE of the
% c2cweb-package (found at the CTAN archives, e.g. ftp.dante.de) and then say
%
%           cweave +a extconv.w
%
% This (fully compatible) CWEAVE can transform CWEB-files with alternative
% output rules (look at the position of braces below!) the author (it's me
% too :-) prefer. Otherwise this file will be formatted traditionally.

\def\title{extconv (CJK Version 4.8.5)}

\def\topofcontents{
  \null\vfill
  \centerline{\titlefont The {\ttitlefont extconv} program}
  \vskip 20pt
  \centerline{(CJK Version 4.8.5)}
  \vfill}

\def\botofcontents{
  \vfill
  \noindent
  Copyright \copyright\ 1996, 1998 by Werner Lemberg
  \bigskip\noindent
  Permission is granted to make and distribute verbatim copies of this
  document provided that the copyright notice and this permission notice
  are preserved on all copies.

  \smallskip\noindent
  Permission is granted to copy and distribute modified versions of this
  document under the conditions for verbatim copying, provided that the
  entire resulting derived work is distributed under the terms of a
  permission notice identical to this one.}

\pageno=\contentspagenumber \advance\pageno by 1
\let\maybe=\iftrue
\fullpageheight=240mm
\pageheight=223mm
\pagewidth=158mm
\setpage
\frenchspacing

\noinx
\nosecs
\nocon

@* Function and Use.
This small program will convert Big~5+ or GBK encoded Chinese characters
into a `preprocessed' form. The need of this program arises from the fact
that these two encodings use the characters `\.{\\}', `\.{\{}', and `\.{\}}'
which have special meanings in \TeX.

Use this program as a filter:

\hskip 2em \.{extconv < input\_file > output\_file}


@* The program.
The only function of this program is to replace all occurrences of Big~5+
and GBK encoded characters \.{XY} (\.{X} and \.{Y} are the first and the
second byte of the character) with
\.{\char94 \char94 7fX\char94 \char94 7fZZZ\char94 \char94 7f}, where \.{ZZZ}
represents the second byte as a decimal number. \.{0x7F} is used as an active
character and delimiter.

Additionally we define a \TeX\ macro at the very beginning to signal a
preprocessed file.

The following code is very simple. No error detection is done because \TeX\
which will see the output of \.{extconv} complains loudly if something is
wrong.

@d banner
"extconv (CJK ver. 4.8.5)"

@c
#include <stdio.h>
#include <stdlib.h>
#ifdef WIN32
#include <fcntl.h>
#include <io.h>
#endif@#


int main(int argc, char *argv[])
   {int ch;

#ifdef WIN32
    setmode(fileno(stdout), _O_BINARY);
#endif

    fprintf(stdout, "\\def\\CJKpreproc{%s}", banner);@#

    ch = fgetc(stdin);@#

    while(!feof(stdin))
       {if(ch >= 0x81 && ch <= 0xFE)
           {fprintf(stdout, "\177%c\177", ch);@#

            ch = fgetc(stdin);
            if(!feof(stdin))
                fprintf(stdout, "%d\177", ch);
           }
        else
            fputc(ch, stdout);@#

        ch = fgetc(stdin);
       }
    exit(EXIT_SUCCESS);
    return 0;       /* never reached */
   }
